Russian carrier UTAir has revised its de-icing procedures, following an order from the federal transport supervisory agency in the wake of the fatal ATR 72-200 crash at Tyumen.
Rostransnadzor told maintenance operation UTAir Technik that, in the period from 30 March to 5 April, four of the carrier's aircraft had flown from Moscow Vnukovo airport without undergoing proper anti-icing, despite the weather conditions.
The incident at Tyumen took place on 2 April, during this period. Thirty-one of the occupants on the twin-turboprop were killed when it came down shortly after its take-off for Surgut.
While Russia's Interstate Aviation Committee is still formally investigating the cause of the crash, there has been increased attention on de-icing, following the discovery that the procedure was not properly conducted.
UTAir Technik states that the crew "had the right, at any moment, to request de-icing", and that Tyumen airport had the facilities and personnel to de-ice the aircraft.
The captain of the crashed turboprop had logged 2,580h while the first officer had accumulated 1,690h. The carrier also emphasises its "strict" adherence to crew training and international practices. UTAir has passed IATA's operational safety audit, and is registered until October 2013.
The airline suspended services with its ATR 72-200s, but reaffirmed its confidence in the turboprop and insisted it would continue services with its newer ATR 72-500s after implementing the procedural changes.
It says the new procedures "exclude error in decision-making on de-icing," adding that de-icing will be carried out in all weather conditions which can contribute to icing on the ground.
UTAir says it put the rules in place after Rostransnadzor had warned of restrictions on its ATR 72 flights, as well as activities by UTAir Technik at Vnukovo. The carrier admits that the revised de-icing regulations will "entail additional costs", but will "dramatically reduce" the risk of incorrect decisions during preparations for departure.